Neural tissue can be artificially stimulated and activated by prosthetic devices that pass pulses of electrical current through electrodes on such a device. The passage of current causes changes in electrical potentials across neuronal membranes, which can initiate neuron action potentials, which are the means of information transfer in the nervous system.
Based on this mechanism, it is possible to input information into the central nervous system by coding the sensory information as a sequence of electrical pulses which are relayed to the central nervous system via the prosthetic device. In this way, it is possible to provide artificial sensations including vision, and interrupt the onset of movement disorders. Additionally, neural stimulation in the brain may be able to modulate obesity, anxiety, depression and other mood disorders.
In 1986, Bullara (U.S. Pat. No. 4,573,481) patented an electrode assembly for surgical implantation on a nerve. The matrix was silicone with embedded iridium electrodes. The assembly fit around a nerve to stimulate it.
US Patent Application 2003/0109903 to Berrang describes a Low profile subcutaneous enclosure in particular, and metal over ceramic hermetic package for implantation under the skin.